1. Field of Invention
The present invention is directed to metal forging and, more particularly, to apparatuses for use in a forging press to near net warm forge relatively complex shaped parts from axi-symmetrical workpieces (billets), and also to a forging methods utilizing the apparatuses to produce such part configurations from such workpieces.
2 Description of Related Art
Known near net warm forging apparatuses and processes can produce parts with high dimensional accuracy. In near net forging, the workpieces (billets) must have approximately the same volume (and weight) as the finished parts. Known near net warm forging apparatuses and processes can generally reduce processing costs by efficient material utilization, simplifying secondary operations, and reducing the number of processing steps.
However, the forged parts will be underfilled if the workpiece volume is too low (underpacked), and the forged parts will have a significant amount of excess material that must be removed by secondary operations if the workpiece volume is too high (overpacked). Also, because near net warm forging dies and punches are usually designed with tight tolerances, use of too large workpieces will cause undue wear of the dies and punches.
Moreover, known near net forging apparatuses and processes are not capable of producing satisfactory parts having certain complex configurations. Exemplary part configurations that can not be produced in a satisfactory manner by near net warm forging are configurations that are curved in one plane and stepped in other planes transverse to the planes in which they are curved. These parts have not been evenly formed by present near net warm forging apparatuses and methods. These configurations are intended as a sample of the part configurations which can not be satisfactorily formed by known near net warm forging apparatuses and methods; there are many other such configurations.
One reason why known near net warm forging apparatuses and processes are unable to satisfactorily manufacture such part configurations is because the apparatuses and processes do not evenly fill the cavities in the dies for forming such parts. If the cavities are not substantially evenly filled, rollover and other forging phenomenon may occur which may result in defective parts.
Another reason why known near net warm forging apparatuses and processes are unable to produce satisfactory parts of certain part configurations pertains to the relationship (i.e., fit) between the workpieces and the die cavities. Specifically, the workpieces must be properly positioned within the die cavities before and during the forging stroke. If the workpieces are not properly positioned, unsatisfactory parts may be produced. The known near net warm forging apparatuses and processes are unable to properly position workpieces if the workpieces do not snugly fit in the die cavity. Thus, the workpieces must be designed to snugly fit in the cavities.
However, there are many part configurations which can not be made from workpieces which snugly fit in the cavity--rather the workpieces are smaller than the cavity in at least one dimension, so that the workpieces can move within the cavity. If known near net warm forging apparatuses and parts are used when workpieces are free to move within the cavity, the resulting parts may not have the specified configuration and may be non-functional. Workpiece size and shape are important considerations in near net warm forging, because, as stated, the workpieces must have substantially the same volume as the finished parts.
The workpieces for near net warm forging also need to be symmetrical because they are dropped into the die cavities either manually or by a machine. The workpieces must fit in the cavities in only one orientation to ensure that they are properly oriented in the die cavities. For this reason, generally cylindrical workpieces are typically used. For certain part configurations, if the workpieces are long enough to engage opposing end walls of the cavities to prevent movement of the workpiece in that direction, the workpieces do not have enough volume to engage the side walls of the cavities. Consequently, the workpieces can move between the side walls. As stated, if the workpieces are not properly located between the side walls, the resulting forged parts may not be evenly filled or formed. Alternatively, the workpieces may be wide enough to engage the side walls of the cavities, preventing movement of the work pieces in that direction, but not have sufficient volume to engage the end walls of the cavities. Improper location exists under this condition.
Thus, if known near net warm forging apparatuses and processes are employed to manufacture parts from workpieces that do not snugly fit in the die cavities, the forged parts must be 100% manually sorted to separate the acceptable and defective parts to ensure that the defective parts are not provided to a customer. The sorting process introduces an added step and added costs into the part forming process. In addition, the defective parts that are eliminated by sorting must be scrapped or recycled. Thus, the known near net warm forming apparatuses and processes neither efficiently utilize material nor optimize the number of processing steps required to produce finished parts in these circumstances.
Thus, there is a need for apparatuses that are suitable for use in a forging press to near net warm forge metal parts having certain relatively complex configurations, and also for methods of near net warm forging such part configurations utilizing the apparatuses, that overcome the above-described problems.